Currently, the new electric propulsion systems comprise a plurality of electric thrusters, such as gridded thrusters or plasma thrusters, which have to be reliabilized in order to cover all the failure cases in the sources of power which supply the electric thrusters and in the components internal to the electric thrusters. For that, it is necessary to be able to equally connect each source of supply in terms of power to any one of the electric thrusters, in case of a single failure or in case of multiple failures.
The current control systems are often designed by using a plurality of mechanical relays interconnecting the sources of supply in terms of power to the electric thrusters. These systems are limited in terms of possible configurations because the mechanical relays have only a single input that can be connected to only two outputs. The failure of a source of supply in terms of power, or power processing unit (PPU), therefore results in the non-operation of two electric thrusters. Moreover, they have a problem of reliability because they do not include any redundancy in the control electronics. Furthermore, these control systems require the use of a large number of power processing units and mechanical relays, which generates significant problems of cost, weight and bulk.
Document US2014/0137537 describes a propulsion system comprising electric thrusters, in particular four gridded ion propulsion nozzles, connected in pairs to two power processing units via two different rotary switches. Each rotary switch has two different positions which respectively select the first or the second power source to supply each electric thruster according to the angular position of a rotary shaft. However, each rotary switch has only two inputs and two outputs and allows for only two different connections. That does not make it possible to fulfill a redundancy function in case of failure, requires the use of a plurality of different switching devices to ensure the supply for a greater number of thrusters, and creates problems of bulk and of additional weight that are prohibitive for an application on a satellite. Furthermore, the rotary switches are defined for gridded electric thrusters and are incompatible with plasma electric thrusters.